Letter to the editor: Pulmonary disease due to rifampin-resistant mycobacterium kansasii in an adolescent

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LETTERS TO THE EDITOR

Dear Editor,

PULMONARY DISEASE DUE TO RIFAMPIN-RESISTANT MYCOBACTERIUM KANSASII IN AN ADOLESCENT

A 16-year-old boy presented with a 2-month history of coughing, sputum production, fatigue and weight loss. He had been vacci-nated with bacilli Calmette–Guerin at 2 months of age, and there was no history of exposure and tuberculosis infection in his fam-ily. Two months before, he had completed a 3-month treatment of rifampicin and doxycycline for brucella sacroiliitis. The chest radiograph showed right hilar adenopathy. Chest computed tomography revealed a 34× 26 mm cystic-necrotic right hilar adenopathy with multiple millimetric nodules in bilateral lung parenchyma (Fig. 1). His tuberculin skin test was 22 mm. Spu-tum for acid-fast bacilli smear was negative.

Treatment was commenced for suspected tuberculosis with iso-niazid (300 mg/day), rifampicin (600 mg/day), pyrazinamide (35 mg/kg/day) and ethambutol (15 mg/kg/day). However, the child’s symptoms continued to worsen with progressive cough and weight loss. Two months later, two sputum samples cultures on Middlebrook 7H11 agar were positive for nontuberculous mycobacteria that later was identified as Mycobacterium kansasii by a commercial nucleic acid probe (AccuProbe; Gen-Probe, San Diego, CA, USA). Antimicrobial susceptibility testing revealed resistance to rifampicin (minimum inhibitory concentration >1μg/mL) but susceptibility to all other agents tested (isoniazid, ethambutol, clarithromycin, moxifloxacin, trimethoprim-sulfamethoxazole and amikacin). Based upon antimicrobial susceptibility results, the treat-ment regimen was subsequently modified as three-drug regimen consisting of clarithromycin (500 mg twice daily), ethambutol (15 mg/kg/ day) and moxifloxacin (400 mg once daily). Negative

sputum culture conversion was achieved at 2 months, and the treatment continued until sputum cultures were consecutively neg-ative for 12 months. After treatment the patient fully recovered.

During follow-up, all immunological investigations were found to be normal, including serum immunoglobulin levels, peripheral blood lymphocyte subsets,in vitro lymphoproliferative response to mito-gens, dihydrorhodamineflow cytometry assay, flow cytometric anal-ysis of interleukin-12Rβ1 cell surface expression on activated T cells, and Interferon-gamma cell surface expression on monocytes. Sero-logical testing for human immunodeficiency virus was negative.

Although rare, M. kansasii can cause pulmonary disease that is clinically and radiologically indistinguishable from pulmonary tuberculosis in paediatric patients with no underlying lung disease or immunodeﬁciency.1,2 _{It is usually sensitive to standard}

anti-tuberculosis drugs expect pyrazinamide, and the recommend drug regimen is isoniazid, rifampin and ethambutol. Rifampin resistance has been associated with treatment failure, and should be consid-ered in patients who had prior rifampin exposure,1_{as in our case.}

Consequently, species identiﬁcation and antimicrobial susceptibility testing for mycobacteria is necessary for adequate treatment.

Meltem Polat 1

Aslınur Özkaya Parlakay2

An_{ıl Tapısız}3

Pınar Çakmak4 1_{Department of Pediatric Infectious Diseases}

Pamukkale University School of Medicine

4_{Department of Radiology}

Pamukkale University Medical Center Denizli,2_{Department of Pediatric Infectious Diseases}

Health Sciences University Ankara Hematology and Oncology Research Hospital

3_{Department of Pediatric Infectious Diseases}

Gazi University School of Medicine Ankara Turkey Conﬂict of interest: None declared.

References

1 Grifﬁth DE, Aksamit T, Brown-Elliott BA et al. An ofﬁcial ATS/IDSA state-ment: diagnosis, treatment, and prevention of nontuberculous myco-bacterial diseases. Am. J. Respir. Crit. Care Med. 2007; 175: 367–416. 2 Tebruegge M, Pantazidou A, MacGregor D et al. Nontuberculous

myco-bacterial disease in children– Epidemiology, diagnosis & management at a tertiary center. PLoS One 2016; 11: e0147513.

Fig. 1 Chest computed tomography showing a 34 × 26 mm cystic-necrotic right hilar adenopathy (arrow) with multiple milimetric nodules in both lungs.

doi:10.1111./jpc.14822

Journal of Paediatrics and Child Health56 (2020) 489